fixup! add AST unit-test

Author: Michael137

clang/unittests/AST/ASTTraverserTest.cpp

@@ -1174,6 +1174,12 @@ struct Pair
     int x, y;
 };
 
+// Tuple-like structure with a `get` method that has a default argument.
+struct Pair2
+{
+    int x, y;
+};
+
 // Note: these utilities are required to force binding to tuple like structure
 namespace std
 {
@@ -1188,6 +1194,12 @@ namespace std
         static constexpr size_t value = 2;
     };
 
+    template <>
+    struct tuple_size<Pair2>
+    {
+        static constexpr size_t value = 2;
+    };
+
     template <size_t I, class T>
     struct tuple_element
     {
@@ -1199,12 +1211,17 @@ namespace std
 template <size_t I>
 int &&get(Pair &&p);
 
+template <size_t I>
+int &&get(Pair2 &&p, int unused = 0);
+
 void decompTuple()
 {
     Pair p{1, 2};
     auto [a, b] = p;
 
     a = 3;
+
+    auto [c, d] = Pair2{3, 4};
 }
 
 )cpp",
@@ -1586,6 +1603,56 @@ DecompositionDecl ''
 |-DeclRefExpr 'p'
 |-BindingDecl 'a'
 `-BindingDecl 'b'
+)cpp");
+  }
+
+  {
+    auto FN = ast_matchers::match(
+        functionDecl(hasName("decompTuple"), hasDescendant(callExpr(hasAncestor(varDecl(hasName("a"),
+                     hasAncestor(bindingDecl())))).bind("decomp_call"))),
+        AST2->getASTContext());
+    EXPECT_EQ(FN.size(), 1u);
+
+    EXPECT_EQ(
+        dumpASTString(TK_AsIs, FN[0].getNodeAs<CallExpr>("decomp_call")),
+        R"cpp(
+CallExpr
+|-ImplicitCastExpr
+| `-DeclRefExpr 'get'
+`-ImplicitCastExpr
+  `-DeclRefExpr ''
+)cpp");
+
+    EXPECT_EQ(dumpASTString(TK_IgnoreUnlessSpelledInSource,
+                            FN[0].getNodeAs<CallExpr>("decomp_call")),
+              R"cpp(
+DeclRefExpr ''
+)cpp");
+  }
+
+  {
+    auto FN = ast_matchers::match(
+        functionDecl(hasName("decompTuple"), hasDescendant(callExpr(hasAncestor(varDecl(hasName("c"),
+                     hasAncestor(bindingDecl())))).bind("decomp_call_with_default"))),
+        AST2->getASTContext());
+    EXPECT_EQ(FN.size(), 1u);
+
+    EXPECT_EQ(dumpASTString(TK_AsIs, FN[0].getNodeAs<CallExpr>(
+                                         "decomp_call_with_default")),
+              R"cpp(
+CallExpr
+|-ImplicitCastExpr
+| `-DeclRefExpr 'get'
+|-ImplicitCastExpr
+| `-DeclRefExpr ''
+`-CXXDefaultArgExpr
+  `-IntegerLiteral
+)cpp");
+
+    EXPECT_EQ(dumpASTString(TK_IgnoreUnlessSpelledInSource,
+                            FN[0].getNodeAs<CallExpr>("decomp_call_with_default")),
+              R"cpp(
+DeclRefExpr ''
 )cpp");
   }
 }